Paper platform for determination of bumetanide in human urine samples to detect doping in sports using digital image analysis.

Development and application of a new, simple, inexpensive, and eco-friendly method is presented for the quantification of bumetanide in human urine samples for the detection of doping in sports. The method involves the use of a paper platform and digital image detection and is based on the reaction between bumetanide, p -dimethylaminocinnamaldehyde (p -DAC), and HCl in a methanolic medium, yielding a colored compound in a delimited area on a qualitative filter paper. The concentrations of p- DAC and HCl were optimized by a chemometric experimental design. After the addition of the reagents to the paper, digital images were obtained by scanning in a multifunctional printer and analyzed using the RGB pattern. The linear bumetanide concentration range was 6.90 × 10−5–1.37 × 10−3 mol L−1 with R 2 = 0.993 and the limits of detection (LOD) and quantification (LOQ) were 3.60 × 10−4 and 1.09 × 10−4 mol L−1, respectively. A SPE clean-up step for the samples were required to eliminate the interference of urinary urea. The recoveries obtained varied from 94% to 105%, indicating the absence of significant matrix effects or interferences in urine samples after clean-up step. The proposed method was successfully applied to the analysis of bumetanide in human urine samples. • Spot test employing a paper platform delimited with hydrophobic barriers • μPAD associated with digital image detection for bumetanide determination • Determination of bumetanide in urine samples for doping sports • The method represents an advantageous alternative to most of the reported methods. [ABSTRACT FROM AUTHOR]